Pyrometer



March 8, 1960 s. N. HOWELL ETAL 2,927,464

PYROMETER Filed Jan. 16, 1956 FIG; l.

TEMP co/vnem MAMS ` CON 7' E01.

MEA/V5 Arran/5ms Uri@ States Patenti() PYROMETER Sabert N, Howell, Huntington, and William Derganc, Centerport, N.Y., assignors to Servo Corporation of America, New Hyde Park, N.Y., a corporation of Y Application January `16, V19156, Serial No. 559,347

Claims. (Cl. 73-7-355) Our invention 'relates to an improved radiation-pyrometerjconstruction' and incorporates refinements over the construction disclosed in copending patent application Serial Number 481,124, filed -January 1l, 1955.

It is an 'object of the invention to provide an improved device of the character indicated.v

vIt is another object to provide a more compact, rugged and reliable optical pyrometer for continuously following electrical signals rellecting optically collected thermal energy.

It is a specic object to provide a pyrometer meeting the above objects and characterized by extended range of thermal response, particularly for temperatures below ambient.

Otherrobjects and.various further features of novelty and invention will be'pointed out or will occur to those skilled in the art from a reading of the following specilication in conjunction with the accompanying drawings. In said drawings, which' show, for illustrative purposes only, preferred forms of the invention:

Fig. 1 is a simplified, longitudinal sectional view through a radiation pyrometer incorporating features of the invention,` together-with a schematic showing of certain vcontrol elements therefor;

f Fig. 2`is`an electrical diagram schematically showing connections to the pyrometer of- Fig. l; and

FigsS'and 4 are simplified diagrammatic, isometric views of alternative cooling mechanisms for the pyrometer ofFig. 1. A

Briefly stated, our invention contemplates application toradia'tion pyrometers of the type disclosed in said copending application. Such pyrometers employ two energyresponsive elements; "one of `which is" continuously" exposed to a reference source, and the other of which is continuously exposed to the unknown source to be evaluated. The reference source may be contained within a capsule and may include an electrical heating element automatically regulated by thermostatic means. It is in the nature of such devices that the range of regulation is definitely limited, so that, for any particular instrument, observations on an unknown source must be made against reference-source conditions that are fairly limited as to range of reference temperature.

In our invention, we provide a heat-exchanger mechalnism in intimate contact with the reference-source caprtemperature of which may be regulated externally of the pyrometer.

Referring to Fig. 1 of the drawings, our invention is `may be adjustably mounted in a barrel 12 on the axis of the housing 10 at one end thereof. Motor means 13 for driving mechanical parts may be contained within a suitably vented rear part of the assembly, the latter being again preferably located on the same predominant longitudinal axis on the assembly.

The detector assembly may comprise two radiationresponsive elements 14-15, shown contained within separate capsules 14-1S'. 'Ihe element within the first capsule 14 is mounted at the focus of the optics 11, and the element 15 within capsule 15 is in` shielded relation to the energy collected by opticsv 11 and is exposed only tov reference radiation from a source 16 vcontained'within a source capsule 16. The source 16 may be an electrical heater'element continuously supplied by means 17 and regulated by thermosta'tic means, such as a bead thermistor 18' within capsule 16 and adjacent the element 16; the means 18 will be understood to respond differentially to the temperature of the capsule 16 and to the temperature of the heater 16.

In vthe form shown, separate choppers 18--19 are mounted on the same shaft 20 and are driven by motor 13 so as simultaneously to expose elements 14-15 and then simultaneously to cut off elements 14-15 from their l respective sources -of radiation. As explained more fully in said application, Ser. No. 481,124, the outputs of the two detectors 14-15 may bel dilerentially evaluated by ampliiermeans 21v and supplied to a phase splitter 22.A A D.C. output signal is available by subjecting-the splitphase signals to synchronous rectification at 23, and to suitableiltering at 24, before recording or displaying at 25. l In'accordance with the invention, the effective range of operation of the instrument is extended by providing means whereby the reference source may be regulated over a substantially increased range of temperatures. This result is achieved by means of a heat-exchanger mechanism, designated generally 26 in Figs. 1 and 2, and substantially enveloping the source capsule 16'. The heat exchanger 26 may be a block of heat-conducting material,

such as copper, having a plurality of Huid-circulating pas-' sages terminated at inlet and outlet connections 27-28,

- extending externally of the housing 10. In Fig. l', we show and means 30 for automatically regulating the tempera-- ture of such coolant; coolant temperature may be regulated by manual means 31 and observed at an external meter 32.

The particular capsule 16 employed in the pyrometer shown in Fig. 1 is of cylindrical configuration, with an opening or window 33 (Fig. 2) at one end thereof. For protection yof the element 16, we prefer that the opening be closed by suitably transparent means, and we have shown a window element 33 of radiation transmitting material, such as arsenic-trisulphide glass. The heatexchanger unit 26 shown in Fig. 3 envelopes a substantial fraction of the cylindrical periphery of the capsule 16 and includes circulatory passages, designated generally 35, for achieving substantially uniform temperature throughout block 26. In Fig. 4 on the other hand, the heat exchanger 36 fully envelopes all parts of the capsule 16 except for the window opening 33 thereof, and

cooling passages 37-38 substantially symmetrically surround the capsule 16 so as to assure utmost uniformity of temperature in the heat-exchanger block 36. Whatever the configuration of the heat-exchanger device, the reference element 15 will be understood to respond to a I `Patented Mar. '8, I

reference temperature representing a definite value intermediate that of the capsule 16' and that of the heater changer fluid, we make possible the establishment oflreference-source temperatures extending 'over arvery substantally increased range beyond those accommodatable by an electrically heated source alone. This improvement is particularly useful in the measurement of temperatures near and below ambient, and the improvement may be embodied in existing structures without substantial modiiication.

While we have disclosed 'our invention in detail for the preferred forms shown, it will be understood that modifications may be made within the scope of theinvention as defined in the claims which follow.

We claim: 1

l. An optical pyrometer, comprising two like infrared responsive electrical elements; areference infraredI heat source in optical alignment withi one of said elements; collecting optics for collecting energy from an unknown source and focusing the same on the other of said elements; a mechanical chopper; means for continuously driving said' chopper so as to simultaneously expose said iirst element to said reference source andv said second element to the unknown source and, in alternation with such exposure, to simultaneously cut ol'said elements from said respective sources; means responsive to the outputs of said elements for producing a signal corresponding to the difference between said outputs, whereby the diierence signal is an indication of the temperature of said unknown source; a liquid heat-exchanger element for said reference source and including inlet and outlet fluid connections extending externally of said pyperiphery of said capsule.

rometer; and means for establishing a temperature-com trolled flow of uid to said heat-exchanger element by way of said connections whereby theV range of temperature measurement may be extended'.

2. An optical pyrorneter, comprising two like infrared" responsive electrical elements, a reference infrared source f "mame-1 reference source, said control means being differentially responsive to the temperature of said heat-exchanger device and to the temperature otf'said reference source whereby the effective range of control ofv temperature of said reference source may be substantially extended beyond thiat available solely through direct electrical control thereo 3. An optical pyrometer, comprising two like thermally responsive electricalelements, a'reference source in optical alignment with one of said elements, collectingoptics for collecting energy from an uknownsource and focusing the same on the other of said elements, said reference source comprising a capsule containing an electrical heater element and means supplying electrical energy thereto, a heat-responsive electrical element within said capsule and disposed for response differentially to the temperature of said capsule and to the temperature of said heater element, saidheater element being in controllingv relation with the electrical energy supplied to said heater element, afliquid cooling device embracing saidcapsule and in heat-transferring relation therewith, and means continuously supplying a flow of temperature-regulated ui'd to said cooling device.

4. A pyrometeraccording to claim 3, in which said' capsule is an elongated, cylindrical configuration having an opening at one end thereof, said opening being exposed to said one element, and in which said cooling device envelopes a substantial fraction of the cylindrical 5. A pyrometer according to claim 3', in which saidI capsule is an elongated, cylindrical configurationhaving an. opening at one. end thereof, said opening beingcxposed to said oneI element, and in Vwhich said. cooling device envelopes the entire cylindrical periphery of said capsule.

References'Cited inthe le'of this patent UNITED STATES PATENTS 1,630,056 Buttolph .v May 24; 192'?v Y 1,716,775 Hayes June 11,1 1929v 1,895,887 Lorenz Jan. 31,(11933` 2,562 ,5-38 Y Dyer Iulyf31,;1i951 2,650,307 Koppus Aug.- 2S,` V1953l 2,665,129 Durbin et al.vv f Ian. 5,A 11954 2,683,794 Briggs et al. July' 13, 1954y 2,761,072 Wormser Aug. 28, 1956 `f FQREIGN PATENTS v950,577 France .Mar. A28,1949

726,581 v,Great Britain Mar. 21.1955 

